Life Span of Animals

Identifying the lifespan of each of the animals is difficult until they are domesticated or observed by keeping them in the zoo. Identifying the age of trees has a definite pattern, as calculating the number of rings. Many have questions to identify the age of the wild animals. Some animals reveal their age through their physical appearance. Like, count of the tooth, changes in bone structure..etc. Bird bands have identification marks to identify their age. But it is definitely going to vary from species to species. While noting the fishes, some groups are clams and some species grow occasionally, and some fishes reproduce seasonally, but it is difficult to maintain a perfect record. These are only a few existing methods to identify the lifespan of most species and the remaining remains unknown and exist in nature. 

Maximum and Average Longevity 

While observing the maximum and average longevity of particular species, taking one from the group may have longevity, and other species from the same group proven false when subjected to critical observation. This puts on risk for researchers to find the maximum life span of the species. The natural calamities, seasonal changes, geographical changes, few hazards are staying as hurdles to find the maximum and average longevity of many species. 

Environmental Influences

The life span of an organism is usually measured by the unit of time. Although it is logically common, they cause some difficulties. According to the first proposal in 1908, aging depends on the expenditure of a fixed amount of vital energy.  While taking this into account, the cold-blooded animals and warm-blooded animals have different metabolism rates and have various exposure to temperature. This automatically influences, while calculating the life span of individual species. It scientifically proves the cold-blooded invertebrates in deep-sea life live longer than the invertebrates live at high temperatures. The rats in the laboratory live longer than the one which is out. This is due to the variations in metabolic rate. Many wild animals undergo a dormant period during their lifetime.  Researchers have confusion on how to include these dormant periods on account of calculating the age of species. This period has the possibility to boost the lifetime of these organisms.  Many small mammals hibernate during some climates. Some arthropods have development arrest during its life cycle. Under these conditions, the metabolic rates stay very low. But many other species do not have such dormant periods. While calculating the lifetime based on total metabolism, this data remains lacking. 

The length of life is controlled by various factors, they are environmental changes and the genetic system of the individual. It is impossible to mention all the environmental factors that affect species.

A Few Cases are:

1. The possibility of killing the numerous same species for specific needs puts them extinct. 

2. The frequent changes in climate develop the new disease may extinct the whole species 

3. Low reproduction rate, or high death rate, or other intrinsic changes may affect the species growth rate. 

Patterns of Survival 

There are three types of survival patterns taken for research. They are listed and explained below. 

1. Accident Curve

2. Selection-acclimation curve

3. Wearing-out pattern. 

For knowing the pattern of survival of species. Consider a group of similar animals from the same environment with the same age. There is no compulsion to take a particular number for study. It is known that no two species are from the same environment, but it is taken for the study. If the group of animals does not undergo any progressive physiological changes, the reason behind the cause of death of animals will remain constant. This has the probability to decrease one-half its former number. The animals that survive here are according to the pattern of the accident curve. This is how many lower animals are sustaining, even many died. This is irrespective of the animal’s age. 

Another group of animals from the same environment are taken for study. They are genetically different from each other. The animals in the group which are poorly adapting to the new environment die easily. And the animals which are fit for surviving in various geographical changes have a long lifespan. This is illustrated in the selection-acclimation curve. 

If the animal continues its reproduction for the long term without any death, then it results in a declining ability of an individual to survive. The more the population varies, the less abrupt the transition from total survival to total death. This is known as the wearing-out pattern.

After analyzing all the patterns, researchers concluded that the wearing-out pattern mostly happens in the laboratory. And environmental accidents also impact the minimum population, but most of the species undergo selection-acclimation patterns. The selection-acclimation pattern is widely noted in wild animals, mammals, fishes, and many invertebrates. They are facing these issues at younger stages.  The accident pattern occurs in fishes and birds, but natural death or death due to old age is rare in these species. Can simply say that the life span of wild animals or others completely depends on the environment, which they live, and its genetics.